javaWeb学习------smbms项目（准备工作、登录注册实现）

smbsm项目 1.准备工作 1.1.环境搭建

1.搭建一个Maven项目（使用idea搭建一个空白的Maven环境）

2.配置Tomcat

3.测试项目是否能跑起来

4.导入项目中会遇到的jar包

在pom.xml文件中导入依赖：servlet、jsp、mysql…


        
        
            javax.servlet
            javax.servlet-api
            4.0.1
            provided
        
        
        
            javax.servlet.jsp
            javax.servlet.jsp-api
            2.3.3
        
        
        
        
            mysql
            mysql-connector-java
            8.0.19
        






        
        
            taglibs
            standard
            1.1.2

5.创建项目包结构

entity-------实体类（对应数据库中的各个表）

Dao------与数据库交互，进行持久化操作

service-------业务逻辑处理

servet--------服务器

filter--------过滤器

util----------工具

1.2.编写实体类

分析项目中需要的几个实体

ORM映射----表关系映射

1.3.编写基础公共类

1.数据库配置文件

driver = com.mysql.cj.jdbc.Driver
url = jdbc:mysql://localhost:3306/smbms?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
username = root
password  = 123456

2.编写数据库的公共类

//数据库操作公共类(包括通过配置文件连接数据库、查询数据库、增删改数据库)
public class Base {
    //连接数据库的四个数据
    private static String driver;
    private static String url;
    private static String username;
    private static String password;
    //静态代码块，在类加载时进行初始化
    static {
        //创建配置文件的对象实例
        Properties properties = new Properties();
        //通过类的反射加载类加载器，把从配置文件中信息转换为输入流
        InputStream io = Base.class.getClassLoader().getResourceAsStream("db.properties");
        //从输入流中读取属性列表
        try {
            properties.load(io);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //对四个属性，通过properties读取的属性进行赋值
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }
    //创建数据库的连接类
    public static Connection getConnection() throws SQLException, ClassNotFoundException {
        //加载类驱动
        Class.forName(driver);
        //通过驱动器管理连接数据库(数据库的url以及用户名和密码)
        Connection connection = DriverManager.getConnection(url, username, password);
        return connection;
    }
    //编写数据库查询公共类
    public static ResultSet execute(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet,String sql,Object[] params) throws Exception {
        //通过预编译
        preparedStatement = connection.prepareStatement(sql);
        //预编译需要向里面赋值,所以需要一个参数的数组params
        for (int i = 0; i < params.length; i++) {
            //由于setObject从1开始，但是我们的数据是从0开始
            preparedStatement.setObject(i+1,params[i]);
        }
        //查询执行用executQuery
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }
    //编写数据库增删改公共类
    public static int execute(Connection connection,PreparedStatement preparedStatement,String sql,Object[] params) throws Exception {
        //通过预编译
        preparedStatement = connection.prepareStatement(sql);
        //预编译需要向里面赋值,所以需要一个参数的数组params
        for (int i = 0; i < params.length; i++) {
            //由于setObject从1开始，但是我们的数据是从0开始
            preparedStatement.setObject(i+1,params[i]);
        }
        //查询执行用executQuery
        int i = preparedStatement.executeUpdate();
        return i;
    }
    //释放资源类
    public static boolean close(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
        boolean flag = true;
        if(resultSet != null){
            try {
                resultSet.close();
                resultSet = null;//GC回收
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                flag = false;
            }
        }
        if(preparedStatement != null){
            try {
                preparedStatement.close();
                preparedStatement = null;//GC回收
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                flag = false;
            }
        }
        if(connection != null){
            try {
                connection.close();
                connection = null;//GC回收
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                flag = false;
            }
        }
        return flag;
    }
}

1.4.编写字符过滤器

//Filter：过滤器 ，用来过滤网站的数据；
//处理中文乱码
//登录验证….
public class CharacterEncodingFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("utf-8");
        servletResponse.setCharacterEncoding("utf-8");
        servletResponse.setContentType("text/html");
        filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {
        Filter.super.destroy();
    }

别忘了到web.xml中进行注册。



    CharacterEncodingFilter
    com.wang.filter.CharacterEncodingFilter


    CharacterEncodingFilter
    
    /*

2.登录功能的实现 2.1.编写前端界面 2.2设置首页

在web.xml中设置：



    login.jsp

2.3编写DAO层登录用户登录界面

//得到要登陆的用户
public User getLoginUser(Connection connection,String userCode) throws Exception;

2.4编写DAO层接口的实现类

public class UseDAO implements UserDAOImpl{
    @Override
    public User getLoginUser(Connection connection, String userCode) throws Exception {
        User user = null;

        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        //先进行判断connection是否为空
        if (connection != null){
            String sql = "select * from smbms_user where userCode=?";
            Object[] params ={userCode};
            resultSet = Base.execute(connection, preparedStatement,resultSet,sql,params);
            if (resultSet.next()){
                user = new User();
                user.setId(resultSet.getInt("id"));
                user.setUserCode(resultSet.getInt("userCode"));
                user.setUserName(resultSet.getString("userName"));
                user.setUserPassword(resultSet.getString("userPassword"));
                user.setGender(resultSet.getInt("gender"));
                user.setBirthday(resultSet.getDate("birthday"));
                user.setPhone(resultSet.getString("phone"));
                user.setAddress(resultSet.getString("address"));
                user.setUserRole(resultSet.getInt("userRole"));
                user.setCreatedBy(resultSet.getInt("createBy"));
                user.setCreationDate(resultSet.getDate("creationDate"));
                user.setModifyBy(resultSet.getInt("modifyBy"));
                user.setModifyDate(resultSet.getDate("modifyDate"));
            }
            Base.close(null,preparedStatement,resultSet);
        }
        return user;
    }
}

2.5编写业务层接口

//用户登录
public User login(String userCode,String password) throws Exception;

2.6编写业务层实现类

public class UserServiceImpl implements UserService {
    //业务层都会调用DAO层，所以我们要引入DAO层
    private UserDAO userDAO;

    public UserServiceImpl(){
        userDAO = new UseDAOImpl();
    }

    @Override
    public User login(String userCode, String password){
        Connection connection = null;
        User user = null;
        try {
            connection = Base.getConnection();
            user = userDAO.getLoginUser(connection,userCode);
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            Base.close(connection,null,null);
        }
        return user;
    }
}

2.7编写LoginServlet

 //servlet：控制层，调用业务层代码
 @Override
 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
     //获取用户名和密码
     String userCode = req.getParameter("userCode");
     String userPassword = req.getParameter("userPassword");
     //和数据库中的用户名和密码进行对比
     UserService userService = new UserServiceImpl();
     User user = null;//这里已经把登录的人查出来了
     try {
         user = userService.login(userCode, userPassword);
     } catch (Exception e) {
         e.printStackTrace();
     }
     if (user != null){//查到此人时
         //将用户的信息放到session中
         req.getSession().setAttribute(Constans.USER_SESSION,user);
         //成功过之后跳转到登陆成功的界面
         resp.sendRedirect("./jsp/frame.jsp");
     }else {//查无此人，无法登录
         //转发会登陆界面，顺带提示
         req.setAttribute("error","用户名或者密码错误");
         req.getRequestDispatcher("./login.jsp").forward(req,resp);
     }
 }

用户信息Session可以写成常量，之后直接调用

public class Constans {
    public final static String USER_SESSION = "userSession";
}

2.8注册servlet



    LoginServlet
    com.wang.servlet.LoginServlet



    LoginServlet
    /login.do

3.登录功能优化 3.1注销功能

思路：注销Session，返回登录页面

public class LoginOutServlet extends HttpServlet {
    //servlet：控制层，调用业务层代码
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //移除Session
        req.getSession().removeAttribute(Constans.USER_SESSION);
        resp.sendRedirect(req.getContextPath()+"/login.jsp");//返回登陆界面
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

注册servlet



    LoginOutServlet
    com.wang.servlet.LoginOutServlet



    LoginOutServlet
    /logout.do

3.2登录拦截器

public class SysFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        // HttpServletRequest是继承自servletRequest，但是父类无法使用子类的方法，故使用强转类型
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        if (request.getSession().getAttribute(Constans.USER_SESSION) == null){
            response.sendRedirect("/error.jsp");
        }else {
            filterChain.doFilter(servletRequest,servletResponse);
        }
    }
    @Override
    public void destroy() {
        Filter.super.destroy();
    }
}

注册过滤器


    
        SysFilter
        com.wang.filter.SysFilter
    
    
        SysFilter
        
        /jsp/*

javaWeb学习------smbms项目（准备工作、登录注册实现）

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